First developer for multilayer color film of the reversal type



Patente'd May 15, 1951 FIRST DEVELOPER FOR MULTILAYER COLOR FILM OF THE REVERSAL TYPE 7 Herman H. Duerr, Einghamton, N. Y., assignor to General Aniline .& Film Corporation, New York, N. ,Y., a corporation of Delaware No Drawing. Application November 18, 1947, SerialNo. 786,811

(Clk- 95-88) 4 Claims. 1

This invention relates to photographic developers and particularly to an improved firstde- Veloper for multi-layer color film of the reversal type.

2 It has been claimed by operators in this field thatthe addition of very small quantities of soluble iodides to photographic developing solutions increases the rate of development, while larger quantities decrease the rate. The function of the soluble idodides is to precipitate insoluble silver salts. When potassium iodide is added to a hydroquinone or a p-monomethylaminophenol sulfate developer in a concentration ranging from 1.6.6 mgs. to 3.3 grams per liter of developer,

silver-halide grains are reduced to metallic silver.

The developing agents heretofore employed contain, in addition to the organic reducing agent such as hydroquinone or p-monomethylaminophenol, a small quantity of potassium bromide and sodium thiocyanate. The potassium bromide lowers the degree of ionization of silver bromide and by reducing the concentration of silver cations restrains development, whereas the sodium thiocyanate dissolves the residual silverhalide, which otherwise would prevent the clearing out of the highlight portions of the image.

In the case of mu1ti-layer color film of the reversal type, it is difiicult to obtain thissilverhalide dissolving effect uniformly in all three emulsion layers. There is a tendency for the sodium thiocyanate to attack the top layer, which is usually the yellow layer, more strongly because of the higher concentration of the silverhalides in this layer; As the developing solution, containing the silver-halide solvent, diffuses deeper into the'layer, the active concentration of the sodium thiocyanate decreases.

It is an object of the present invention to provide an improved photographic developer, for ,multi-layer color film of the reversal type, in which action of the silver-halide solvent is effectively controlled.

Another object is to provide an improved first developer for reversal multi-layer color film which restrai-ns the development of the yellow top layer and produces-a greater density in such layer.

I have found that the foregoing undesirable effect on the yellow layer of a multi-layer color film of the reversal type, can be counteracted and controlled by the addition of a small quantity of potassium iodide to any black and white developing agent employed in the first development of color film and containing potassium bromide and a silver solvent. The presence of potassium iodide in an amount ranging from 2 to 12 mgs. per liter of developing solution, counteracts the efiect of the silver solvent in the top layer as follows: The iodide ion is absorbed on the silver bromide crystal, in some cases ac-' tually replacing the bromideion inthe-latti'ce of the silver-h-alide.- The absorbed iodide ion greatly reduces the solubility of the silver ha-lide crystal in the silver solventsuch as sodium thiccyanate, etc. Since the largest concentration {Of iodide ion is present in the top layer, the addi.- tion of small quantities of potassium iodide to the developer insures a means of balancing out the effect of the silver solvent inits more vigorous action on the top layer. Surprisingly, po-

tassium iodide in an amount greater than IZ-mgs;

per liter of developer does not show this balancing-out effect. 'As a matter of fact, the presence of potassium iodide in the -,developer in an amount greater than 1'2 mgs. per liter shows .a tendency to restrain development in alllayers, i. e., yellow, magenta, and cyan layers.

Photographic multi-layer color materials, which may be developed with the first developer in ac-- cordance with the present invention, include all color reversible film. Such-color reversible film consists of an integral tripack emulsion coated on the usual clear cellulose acetate or nitrate filmbase. Each of the emulsions is sensitized toone of the primary colors, namely, blue, green, and red. The top layer is blue sensitive; The filter layer, yellow in color and blue absorbing, lies A 4" x multi-layer color film sheet of the reversal type, such as prepared according to United States Patents 2,179,228; 2,179,239; 2,186,- 849 and 2,220,187, was exposed and developed for minutes at 68 F. in a developer of the following composition:

p-Monomethylaminophenol sulfate grams 3 Sodium sulfite do 50 Hydroquinone do 6 Sodium carbonate (monohydrate) do 40 Potassium bromide do 2 Sodium thiocyanate do 2 Potassium iodide mgs 3 Water to make 1 liter.

The developed film was short stopped for 3 minutes in a 3% aqueous solution of acetic acid, and washed for 2 minutes in running water.

The washed film was given a second exposure for 3 minutes to light of a N0. 1 photofiood lamp 30 inches away from the film.

The reexposed film was color developed for minutes in a developer of the following composition:

Sodium sulfite grams 5 p-Diethylaminoaniline hydrochloride do 4 Sodium carbonate do 40 Potassium bromide do 1 Water to make 1 liter.

The color developed film was rinsed for 1 minute in running water, and hardened for 5 minutes in a 3% aqueous solution of chrome alum.

The hardened film was washed for 5 minutes in running water, and bleached for 10 minutes in a bath of the following composition:

Grams Potassium ferricyanide 60 Potassium bromide 15 Disodium phosphate 13 Sodium bisulfate 6 Water to make 1 liter;

The bleached film was then washed in running water for 5 minutes, fixed in a solution of hypo for 5 minutes, Washed for another 5 minutes in running water and then dried.

The resulting transparency was of superior quality and showed a greater density in the top yellow layer with a pleasing color balance in all layers.

Instead of employing sodium thiocyanate as the silver-halide solvent, ethylenediamine or its salts such as the sulfate, chloride, tc. and ammonium chloride may be employed in a concentration ranging from 1 to 8 grams per liter of developer. Similarly, instead of employing p-monomethylaminophenol sulfate as the reducing agent in the first developer, any reducing agent which is normally employed in black and white developers may be used, provided it does 4 not color or stain the mutilayer film as pyrogallol does.

I claim:

1. In the process of restraining the development of the yellow layer in a multi-layer color film of the reversal type which includes exposing said film, developing it with a first developing bath for silver halide, re-exposing to light, color developing and bleaching the same, the improvement comprising using as the first developing bath an aqueous developing solution comprising a developing agent for silver-halide, potassium bromide, a silver solvent, and potassium iodide in an amount ranging from 2 to 12 mgs. per liter of developer.

2. The process according to claim 1 wherein the silver solvent is a member selected from the class consisting of sodium thiocyanate, ammonium chloride, and ethylenediamine and its salts.

3. In the process of restraining the development of the yellow layer in a multi-layer color film of the reversal type which includes exposing said film, developing it with a first developing bath for silver halide, re-exposing to light, color developing and bleaching the same, the improvement comprising using as the first developing bath an aqueous developing solution comprising a developing agent for silver-halide, potassium bromide, sodium thiocyanate, and potassium iodide in an amount ranging from 2 to 12 mgs. per liter of developer.

4. In the process of restraining the development of the yellow layer in a, multi-layer color film of the reversal type which includes exposing said film, developing it with a first developing bath for silver halide, re-exposing to light, color developing and bleaching the same, the improvement comprising using as the first developing bath solution of the following composition:

p-Monomethylaminophenol sulfate grams 3 Sodium sulfite do 50 Hydroquinone do 6 Sodium carbonate (monohydrate) do 40 Potassium bromide do 2 Sodium thiocyanate do 2 Potassium iodide mgs 3 Water to make 1 liter.

' HERMAN H. DUERR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 838,488 Williams Dec. 11, 1906 1,482,613 John Feb. 5, 1924 1,954,337 Stand Apr. 10, 1934 2,091,713 Mannes et a1. Aug. 31, 1937 2,136,968 Doran Nov. 15, 1938 2,159,600 Murray et al. May 23, 1939 2,191,037 Mannes et a1. Feb. 20, 1940 2,371,740 Dearing et al. Mar. 20, 1945 2,388,816 Bean Nov. 13, 1945 FOREIGN PATENTS Number Country Date 470,855 Great Britain Aug. 23, 1937 

1. IN THE PROCESS FO RESTRAINING THE DEVELOPMENT OF THE YELLOW LAYER IN A MULTI-LAYER COLOR FILM OF THE REVERSAL TYPE WHICH INCLUDES EXPOSING SAID FILM, DEVELOPING IT WITH A FIRST DEVELOPING BATH FOR SILVER HALIDE, RE-EXPOSING TO LIGHT, COLOR DEVELOPING AND BLEACHING THE SAME, THE IMPROVEMENT COMPRISING USING AS THE FIRST DEVELOPING BATH AN AQUEOUS DEVELOPING SOLUTION COMPRISING A DEVELOPING AGENT FOR SILVER-HALIDE, POTASSIUM BROMIDE, A SILVER SOLVENT, AND POTASSIUM IODIDE IN AN AMOUNT RANGING FROM 2 TO 12 MGS. PER LITER OF DEVELOPER. 